Ignore spurious warnings in test_quiet_close_process

[crusaderky]

Closes #6582
Of course, an exceptionally slow VM could print out "Creating scratch directories is taking a surprisingly long time" five times in a row - we'll iterate again if it happens.

[fjetter]

A different approach could be to change the client script to

import warnings
from dask.distributed import Client
allowed_warnings = [
    ...
]
if __name__ == "__main__":
    for msg in allowed_warnings:
        warnings.filterwarings("ignore", msg)
    client = Client(processes=%s, n_workers=1, scheduler_port=0, dashboard_address=":0")

I'm OK either way

[crusaderky]

@fjetter my approach however has the advantage that, if the spurious warnings start cropping up every time, the test will fail.

[github-actions]

Unit Test Results

See test report for an extended history of previous test failures. This is useful for diagnosing flaky tests.

       15 files  +       1         15 suites  +1   6h 43m 29s ⏱️ + 1h 5m 2s
  3 044 tests ±       0    2 957 ✔️ +     12    84 💤  - 11  3 ❌  - 1 
22 514 runs  +1 819  21 536 ✔️ +1 807  975 💤 +13  3 ❌  - 1 

For more details on these failures, see this check.

Results for commit 4c01945. ± Comparison against base commit b8d1c7b.